What is considered the least desirable preservative used on poles?

Creosote is considered the least desirable preservative used on poles due to several factors related to its health and environmental impacts. This oily, dark substance is derived from the distillation of softwood creosote and has been widely used for its ability to protect wood from decay and insect damage. However, creosote is classified as a probable human carcinogen, raising serious health concerns for workers handling treated materials and for nearby communities.

Additionally, creosote can leach into the soil and groundwater, potentially contaminating local ecosystems. The environmental consequences of its use have led to increased regulatory scrutiny and restrictions. As a result, other preservatives, which may offer a more favorable risk profile or environmental consideration, are often preferred over creosote in modern applications. This is why, in the context of safety and environmental regulations, creosote is viewed as the least desirable option among the preservatives listed.